Fraternal twin one baby is haemophilic while baby's brother is normal then which statement is true

Options

A. Baby is male
B. Baby is female
C. Mother is heterozygous
D. Mother is homozygous

Answer

To solve the question regarding fraternal twins where one baby is hemophilic and the other is normal, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Fraternal Twins**:
- Fraternal twins, also known as dizygotic twins, occur when two separate eggs are fertilized by two separate sperm cells. This means that each twin has a different genetic makeup.

**Hint**: Remember that fraternal twins come from two different eggs and sperm, leading to different genetic traits.

2. **Identify the Condition**:
- One twin is hemophilic, which means he has hemophilia, a genetic disorder that affects blood clotting. Hemophilia is typically X-linked recessive, meaning that the gene responsible for hemophilia is located on the X chromosome.

**Hint**: Recall that hemophilia is linked to the X chromosome and is more common in males due to their XY chromosome configuration.

3. **Determine the Genetic Makeup**:
- Since one twin is hemophilic, he must have inherited the hemophilia allele (Xh) from his mother. The normal twin must have inherited a normal X chromosome (X) from the mother.

**Hint**: Consider how X-linked traits are passed from mother to son, especially in the context of hemophilia.

4. **Analyze the Mother's Genotype**:
- The mother must be a carrier of the hemophilia gene (XhX) because she has one affected son (hemophilic) and one unaffected son (normal). If she were affected (XhXh), both sons would be hemophilic.

**Hint**: Think about how the mother’s genotype affects the sons’ phenotypes and the implications of being a carrier.

5. **Consider the Father's Genotype**:
- The father of the twins must have a normal genotype (XY) since he cannot pass on the hemophilia allele (he has only one X chromosome).

**Hint**: Remember that males inherit their X chromosome from their mother and Y chromosome from their father.

6. **Conclusion**:
- The true statement is that the mother is a carrier of hemophilia (XhX), and the father is normal (XY). The affected twin is hemophilic (XhY), while the unaffected twin is normal (XY).

**Hint**: Summarize the genotypes of the parents and how they contribute to the phenotypes of the twins.

### Final Answer:
The correct statement is that the mother is a carrier for hemophilia (heterozygous), and the father is normal.